nuke and particle physics

Question 1

what is an isotope

Answer 1

same number of protons; diff number of neutrons

Question 2

what nuclear forces act on hadrons

Answer 2

both strong and weak

Question 3

what is a hadron

Answer 3

subatomic particle made up of quarks

Question 4

what are the two types of hadrons

Answer 4

baryons and mesons

Question 5

what are baryons

Answer 5

hadrons made of three quarks

Question 6

what are mesons

Answer 6

hadrons made of a quark and antiquark

Question 7

what interaction causes beta decay

Answer 7

weak nuclear force

Question 8

an alpha particle is fired at a stationary gold nucleus; at one point the alpha is stationary and the gold has velocity; explain what happened

Answer 8

electrostatic repulsion between the particles; momentum conserved due to no external force; so gold has (lower) velocity; KE of alpha particle converted to electric PE

Question 9

which type of decay produces a normal neutrino

Answer 9

beta plus decay (antineutrino for beta minus)

Question 10

why are protons and neutrons not fundamental particles

Answer 10

they are made up of quarks

Question 11

name some leptons

Answer 11

electron; positron; neutrino; antineutrino

Question 12

what nuclear forces act on leptons

Answer 12

only weak

Question 13

how did the alpha scattering experiment give evidence for the nuclear model of the atom

Answer 13

most alpha particles went straight through, showing most of the atom is empty space; some were scattered, showing a dense positive nucleus

Question 14

what is the binding energy of a nucleus

Answer 14

min energy to separate all nucleons

Question 15

what is mass defect

Answer 15

change in mass due to binding energy (energy change due to forming a nucleus)

Question 16

why is the mass of a nucleus different from the total mass of its nucleons

Answer 16

energy released to form nucleus from nucleons; E = mc^2, so mass of nucleus is smaller

Question 17

explain nuclear fusion; refer to the conditions needed

Answer 17

electrostatic repulsion between nuclei; high temperature and pressure required to overcome it; nuclei get close enough for strong force to start acting; overall decrease in mass occurs, releasing energy

Question 18

why is radioactive decay said to be spontaneous and random

Answer 18

spontaneous - cannot be induced; random - time of next decay cannot be predicted

Question 19

explain the technique of carbon dating

Answer 19

living things take in C-14; they stop once dead; activity of C-14 is measured in both a dead and living sample; equation used with this data to estimate age

Question 20

explain why carbon dating has an age limit

Answer 20

activity becomes so low you can’t tell it from the background

Question 21

what physical properties make nuclear waste dangerous

Answer 21

radioactivity causes ionisation; can be active for a long time

Question 22

explain induced nuclear fission

Answer 22

a slow moving neutron splits a nucleus into two smaller nuclei + fast moving neutrons; overall decrease in mass occurs, releasing energy

Question 23

state and explain the purpose of a moderator in a nuclear reactor; include how it works at a microscopic level

Answer 23

moderator slows down neutrons; nuclear fission produces fast moving neutrons; they collide with moderator atoms and pass on their KE; slow moving neutrons can cause more fission (chain reaction)

Question 24

what are control rods used for in a nuclear reactor

Answer 24

they absorb neutrons

Question 25

describe the nature of the strong nuclear force

Answer 25

acts between hadrons; short range

Question 26

two protons fuse together; explain how they are able to remain together

Answer 26

strong nuclear force makes them attract